I don't know why Catherine hasn't worn the tiara since then. There's two State events coming up this year, perhaps she'll give it a go again.

The Halo tiara was loaned for an exhibition that was going on in Paris not too long after the wedding and I can't remember how long it ran. We may see the Duchess wear it again or she may have decided that the Lotus Tiara is more comfortable or to her taste.

Is the Sapphire Bandeau still with the British Royal family or was it sold off?

Most likely still with the royal family in the vaults. The Queen have lots of jewels in the collection that haven’t seen the light of day in decades. I think some may need to be reframed and cleaned. The new generation of royals can bring them out again.

__________________"WE CANNOT PRAY IN LOVE AND LIVE IN HATE AND STILL THINK WE ARE WORSHIPING GOD."

It's not known. It's either with the Queen or with Margaret's children. If it's with Margaret's children, it wasn't put up for auction with some of Margaret's jewels after her death unless it was sold privately.
I'm betting it's in the Queen's possession.

It’s a good starter tiara. Very simple and elegant for when a senior royal lady don’t feel like dealing with the big guns at a State Opening of Parliament, State Visit, Royal Wedding or Diplomatic Corps Reception. Sadly the royals don’t go to events like the opera anymore. They used to wear their tiaras and family orders at those events back in the day.

__________________"WE CANNOT PRAY IN LOVE AND LIVE IN HATE AND STILL THINK WE ARE WORSHIPING GOD."

One of the most beautiful tiaras of all times next to the Girls that HM wears. These are my 2 very favorite tiaras ever. Just so sad it is now gone like so many others that have disappeared in time. The workmanship and design on this one is just marvelous.